Please Help! 10 mL of blood is withdrawn from a dog (with his consent, of course
ID: 54896 • Letter: P
Question
Please Help!
10 mL of blood is withdrawn from a dog (with his consent, of course!). After centrifugation to remove the plasma, 4 mL of packed red blood cells remain. The number of cells is determined microscopically to be 8 million per mm3. Microscopic observations also suggest that a single red blood cell can be modeled as a cylinder with a height of 1 m and a diameter of 7 m. The packed red cells are extracted with chloroform to isolate the total membrane phospholipids, the extract is carefully layered onto the surface of a hot water bath, and the chloroform is evaporated to leave a surface film of phospholipid. Under proper conditions this film represents a single layer oriented such that the polar head groups are adjacent to the water and the hydrophobic tails are pointing into the air, with the molecules packed tightly together. The total surface area of this monolayer film is 6 m2. Show that these data are consistent with the phospholipid bilayer model of the cell membrane.
Explanation / Answer
The formula for calculation of area is:
The RBC/mm3 = 8×106
The surface of area of RBC is:
Thus, the surface area of one RBC is:
Now the surface area of 8×106 cells is:
Usually, the RBC is in double layered and the above obtained surface area is for double layer membrane.
If this RBC is subjected to procedure that is mentioned in the question, then it will form a single monolayer with surface area.
Therefore, yes the given data is consistent with the phospholipid bilayer model of the cell membrane.